Some network equipment is designed for installation within a standard electronic equipment rack (e.g., a conventional 19-inch rack). Such equipment typically includes a housing which mounts to the equipment rack, a set of circuit boards disposed within the housing, and a fan assembly which is disposed within the housing. During operation, the fan assembly moves ambient air at the front of the equipment rack past the set of circuit boards and out the back of the equipment rack. As the ambient air flows across the set of circuit boards, the air removes heat from the circuit boards thus enabling the electronic circuitry on the circuit boards to operate within a controlled temperature range while performing a variety of network operations (e.g., routing operations, switching operations, etc.).
One conventional network equipment design (hereinafter referred to as the “horizontal design”) includes a housing having an air inlet at the front of equipment rack and air outlet at the back of the equipment rack. The air inlet and the air outlet are at substantially the same height, and a fan assembly within the housing moves air from the air inlet to the air outlet through the housing and past the set of circuit boards in a substantially horizontal manner for robust heat dissipation.
Another conventional network equipment design (hereinafter referred to as the “up/across/up design”) includes a housing having an air inlet at the front of equipment rack and air outlet at the back of the equipment rack with the air outlet at a substantially higher height than the air inlet. The circuit boards are horizontally-oriented, i.e., the circuit boards reside parallel to each other and substantially parallel to the floor. During operation, the fan assembly moves air from the air inlet in an upward direction within the housing. The air further moves horizontally across the horizontally-oriented circuit boards and then again in the upward direction and out of the housing through the air outlet.